Method of obtaining pure gum from some crude gum materials and apparatus therefor



Jul '27, 1926. 1,593,964

N. BUCHAN METHOD OF OBTAINING PURE GUM FROM SOME cnuns GUI MATERIALS AND APPARATUS THEREFOR Filed June 18, 1925 Patented July 27, 1 926.

UNITED STATES PATENT OFFICE.

. KIVEN IBUCHAN, OF. AUCKLAND, NEW ZEALAND.

HETHOD OI OBTAINING PURE GUM FROM SOME CRUDE GUM MATERIALS AND APPARATUS THEREFOR.

Application filed June 18, 1925, Serial No.

This invention concerns kauri-gum and has as its object to provide a method for yielding a purified kauri-gum more suited for its various technical applications such as,

I forinstahce, in varnish making, than that usually obtainable. I

Kauri-gum is a copal resin found in nature principally in New Zealand and chiefly in the Auckland Province. It is usually associated with many impurities and-even after separation of the foreign matters by washing, sieving, flotation and the like the lower grades still contain impurities such as decomposed kauri-gum, wood, charcoal l and mineral matter which'render the gum of low value.

According to this invention crude kaurigum is extracted with a solvent consisting of ethyl etherora mixture of ethyl ether and !0 a volatile hydrocarbon and ,having the property of dissolving out the pure gum and t e essential oils, while leaving the undissolved matters'behind, the extract being subjected to volatilization so that the final product is I5. purified kauri-gum containing essential oils in solid form. I

The following serves to illustrate how the invention is carried into effect:

The lower grade gum is stirred with a W sufiicient volume of a mixture of ethyl ether and benzine until the pure gum dissolves. The mixture is then allowed to settle so that the impurities are precipitated. The clean solution is then run into a still and the 5 solvent recovered by distillation, whereu on there remains clean kauri-gum which w ile .hot is sufliciently fluid to be run into open rece tacles in which on cooling the solid bl s or lumps are formed and from which 0 they can be removed. V The grade of kauri-gum most suited to my process is that which is low in market value and as high as possible in undecomposed kauri-gum content. It is preferable to have the material in powdered form, say

to as a mesh screen or finer, thus assist ng quick solution. The powdered gum should be 4 dried either .by thorough sun d or by artificial means at temperatures ll be ow 100 C. Prolonged drying at temperatures over 100 C. causes polymerization of the gum which thus becomes insoluble. The proportions of 'the solvents, when a of ethyl ether and a hydrocarbon l 'is used, may be varied, but that foundjmost importance because the essential oil kaurigum is what determines its superiority over decanting valves 18 at 39,993, and in New Zealand July as, 1924.

convenient is one volume of ethyl ether to two volumes of benzine. When making up losses of solvent, the initial hydrometer reading' of the mixture is maintained by adding ethyl ether to lower and benzine to raise the 60 specific gravity. 'The volume of the mixture best-suited to complete solution and to rapid settling of the impurities is about seven pints to the pound of pure kauri gum to be dissolved. There must always be sufiicient 05 ethyl ether present to ensure the complete solution of the gum. Decomposition caused by the combination of bases principally 'lime andiron with the organic acidsof the gum, is accompanied by the liberation of oils. This oil. in so far as it remains attached to the material treated is taken up by the solvent and enters into the composition of the finished extracted product. This point is of other copal resins as a flux or medium. The product is also distinguished from the naturally occurring fossil kauri-gum by its freedom from inclusions and encrustations.

A suitable apparatus according to my invention is illustrated in the accompanying drawings showing a sectional elevation thereof.

The extractor 1 is a cylindrical vessel in the inside of which near the bottom is an agitator 2 attached to a shaft 3 mounted in a bearing 4. p

The upper end of shaft 3 passes out of extractor 1 through a stufiin box 5 and is rotated by means of-bevel w eels 6 and 7, pulleys 8, and shaft 9, mounted in pedestal bearings 10 and 11. To the top of the extractor 1 is fitted a char g hole 12 with door 13 directly above wii supply hopper 14. To the side nearthe bottom of extractor 1* the discharging hole 15 with door 16 is fitted and also to the side is fitted a liquid geuge 17 and three 'iferent levels. To the extractor 1 is also fitted a steam pipe 19 with valve 20; a low pressure safety valve 21; solvent supply ipe 22 with valve 23 and solvent vapour discharge pipe 24 with valve 25. J The, decanting valves 18 lead 1 to a strainer 26 and from thence throu h valve 27 to the still 28 which is an airtig tcylindrical vessel. Inside and at the bot tom of the still 28 there is a steam coil 29, I with steam supply valve 30 and steam trap 1 0 ch is placed the 05 I condensed vapour passes from the condenser I 36 to a water separator 40 which is another cylindrical enclosed vessel the pipe 39 inside water separator 40 having a branch 41 for air releasing.

To the side of the water separator 40 is fitted a liquid gauge 42 and to the bottom a water drain pipe 43 with valve 44 and vflexible joint 45 for length extending or reducing. To the side near the top of the water separator 40 is fitted the solvent discharge pipe 46 which passes to a" sight gauge 47 with glass inspection cover 48 and from the sight gauge 47 to the solvent storage tank 49 which is a cylindrical air tight vessel. To the top of the storage tank 49 is fitted an air valve 50; to the side a liquid gauge 51; to the bottom a water drain valve 52 also the. solvent supply pipe 53 which passes a short.distance inside to get above the water. To the solvent vapour pipe 34 just below the valve 35 is connected a vapour suction pipe 54 with valve 55. This pipe 54 leads to a vacuum pump 56 which delivers through delivery pipe 57 to the condenser 36. To operate the apparatus considering all valves and doors closed, the charging door 13 is opened and 'a charge of dried powdered gum with impurities admitted to the extractor 1 from hopper 14; the door 13 is then again closed. Valves 23 and 25 are opened, allowing the quantity of solvent required (benzine and ethyl ether 53 into the extractor 1, the displaced air passin to the condenser 36 through valve 25 an pipes 24 and 34the-valves 23 and 25 being then again closed. The agitator 2 is set in motion, and the solvent quickly dissolves the gum. The agitator 2 is stopped and the solution allowed to settle, the level of separation between the pure solution and the undesirable foreign matter such as Wood, charcoal, gum dirt and mucilagebeing ascer tainable by the liquid gauge 17 the pure solution being uppermost. The decanting valve 18 nearest above the separation level is turned on and with valve 27 also turned on the pure solution flows oil through strainer 26 into the still 28, the valves 18 and 27 being then turned off. Valve 35 is then turned on and the circulating water admitted to the surface condenser 36. Valve 30 is turned on admitting steam at 130 lbs. per square inch to the steam coil 29 thus raising the temperature of the solution in to flow through pipes 22 and 'or decrease the still 28. This heating of the solution causes vapourization of the solvent which passes through valve 35 and pipe 34 to the surface condenser and is there again liquefied.

VVhen'the solvent is being removed from the still it is necessary to be able to de-' termine when it is all removed; this is discovered by inspecting the sight gauge 47 the glass cbver 48 enabling inspection to see when the flow of solvent ceases, indicating the removal of the solvent from the sti The valve 35 is then closed and .valve 55 opened and vacuum pump 56 set in motien a vacuum being created in the still 28- as indicated'by the combined vacuum and pressure gauge 33.

This vacuum removes the last traces of solvent from the still 28 leaving only pure gum kept in liquid state by the heat of the steam coil 29; The solvent vapour drawn from the still .28 by the vacuum pump 56 is delivered to the condenser through pipe 57. Vacuum pump 56 is then stopped and valve 55 closed the pure gum being run off through cook 32 and the valve 58 is opened to admit air and break the vacuum the steam valve 30 being then shut ofi'. e

To exhaust the refus'e in extractor 1 of its undccomposed gum contents, the refuse can be washed with small quantities of solvent each washing after settling being decanted off to the still 28.

. To remove all the solventfrom extractor 1 the vapour discharge valve 25 is opened and steam blown upon the gum refuse by turning on the steam valve 20 and setting agitator 2 in motion. This forces all the solvent vapour through discharge p1pe 24 and valve "25 up to the condenser 36 by pipe 34.

Valves-20 and 25 are then shut off, the

from the solvent and this is done by the water separator 40 in which the water setties to the bottom, the separation level being indicated by the liquid gauge 42.

The solvent flows away from the water Y separator 40 through pipes 46 and sight gauge 47 into the solvent storage-tank 49. The water in the water separator 40 can be kept at one level by the height of the water. drain (pipe 43 which can be increased as desired by attaching a longer or shorter pipe 43 to: the flexible joint 45.

The specific gravity of the solvent being or to admit air less than water, the column of water inthe drain pipe 43 will support the smaller column of water in the separator 40 plus the column of solvent from the separation level to the discharge pipe 46,

A water drain valve 52 is fitted to the bottom of the solvent storage tank 49 to 'drain off any water which may collect as indicatedin the liquid gauge 51.

An air valve 50 is fitted to the top of the solvent storage tank 49 to allow escape if desired to the system.

I claim:

gum from crude kauri-gum consisting in drying and crushing. the crude material,

agitating the same with a solvent consisting of ethyl ether or a mixture-0f ethyl ether and a volatile hydrocarbon for extracting the pure gum and the essential oils, and separating the solvent from the extract by volatilization.

'In testimony whereof he aifixes his signature.

NIV'EN BUCHAN. 

